More on Adamantene

Bian, Nanying; Jones, Maitland

doi:10.1021/ja00140a009

Cited by 20 publications

(11 citation statements)

References 3 publications

(3 reference statements)

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“…Other examples of prepared anti‐Bredt compounds include bicyclo[2.2.2]oct‐1‐ene ( G ) (Figure ), 8‐methylenebicyclo[3.2.1]octa‐1,6‐diene ( H ) (Figure ), and bicyclo[3.2.2]nona‐1,6,8‐triene ( I ) (Figure ); all of these compounds are highly reactive. Adamantene ( J ) (Figure ) and substituted analogues have been prepared. DFT computations of adamantene by Shustov and Liu indicate that the singlet is lower than the triplet state by 11.4 kcal mol −1 .…”

Section: Introductionmentioning

confidence: 99%

The quest for a triplet ground‐state alkene: Highly twisted C═C double bonds

Hommes

Lenoir

et al. 2019

J of Physical Organic Chem

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Density functional theory and extrapolated CCSD(T) computations of several "anti-Bredt" alkenes were carried to explore possible 1,2-diyl "alkene" candidates with a triplet ground state. Ten candidates containing twisted double bonds at the bridgehead positions of bicyclic structures (1-6) or adamantene (7-10) derivatives were studied. Based on a combination of ring strain, rigid scaffolding, and steric crowding, four species were identified to have surprisingly low singlet-triplet energy gaps (lower than 4 kcal/mol). A tert-butyl substituted bicyclic structure (4) was identified to have a near-zero singlettriplet energy gap, but no triplet ground-state alkene was found. Ring strain energy (RSE) calculations, π-orbital axis vector (POAV) analyses, and multiple linear regression models were performed to elucidate the geometric and energetic effects of double bond twisting in 1-10. Based on our computational exploration, it appears unlikely that there is a ground-state triplet olefin.

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Section: Introductionmentioning

confidence: 99%

The quest for a triplet ground‐state alkene: Highly twisted C═C double bonds

Hommes

Lenoir

et al. 2019

J of Physical Organic Chem

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Section: Introductionmentioning

confidence: 99%

“…The Jones ,− and Michl ,, groups were the among first to study and use bridgehead carbenes as a route to bridgehead alkenes . Among the compounds they studied were adamantene ( 3a ) − ,, and homoadamantene ( 3b ). ,− The Platz group generated 3a and 3b photochemically from noradamantyldiazirine ( 1a ) and adamantyldiazirine ( 1b ), respectively (Scheme ). , The photochemistry of both noradamantyldiazirine ( 1a ) and adamantyldiazirine ( 1b ) is quite complex. In 2001, Platz and co-workers reported that the photolysis of noradamantyldiazirine ( 1a ) leads to adamantene ( 3a ) through the excited state of the diazirine, bypassing noradamantylcarbene ( 2a ). , They computed the singlet 2a ⇌ 3a equilibrium to greatly favor 3a by 32.4 kcal/mol (B3LYP/6-31G*) and a nominal 0.35 kcal/mol barrier for the conversion of singlet adamantylcarbene to adamantene …”

Section: Introductionmentioning

confidence: 99%

Experimental and Computational Mechanistic Investigation of Chlorocarbene Additions to Bridgehead Carbene–Anti-Bredt Systems: Noradamantylcarbene–Adamantene and Adamantylcarbene–Homoadamantene

et al. 2015

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Cophotolysis of noradamantyldiazirine with the phenanthride precursor of dichlorocarbene or phenylchlorodiazirine in pentane at room temperature produces noradamantylethylenes in 11% yield with slight diastereoselectivity. Cophotolysis of adamantyldiazirine with phenylchlorodiazirine in pentane at room temperature generates adamantylethylenes in 6% yield with no diastereoselectivity. (1)H NMR showed the reaction of noradamantyldiazirine + phenylchlorodiazirine to be independent of solvent, and the rate of noradamantyldiazirine consumption correlated with the rate of ethylene formation. Laser flash photolysis showed that reaction of phenylchlorocarbene + adamantene was independent of adamantene concentration. The reaction of phenylchlorocarbene + homoadamantene produces the ethylene products with k = 9.6 × 10(5) M(-1) s(-1). Calculations at the UB3LYP/6-31+G(d,p) and UM062X/6-31+G(d,p)//UB3LYP/6-31+G(d,p) levels show the formation of exocyclic ethylenes to proceed (a) on the singlet surface via stepwise addition of phenylchlorocarbene (PhCCl) to bridgehead alkenes adamantene and homoadamantene, respectively, producing an intermediate singlet diradical in each case, or (b) via addition of PhCCl to the diazo analogues of noradamantyl- and adamantyldiazirine. Preliminary direct dynamics calculations on adamantene + PhCCl show a high degree of recrossing (68%), indicative of a flat transition state surface. Overall, 9% of the total trajectories formed noradamantylethylene product, each proceeding via the computed singlet diradical.

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“…Both species can be generated photochemically from 3‐noradamantyldiazirine ( 6 ) and are in a photochemical equilibrium with carbene 7 under matrix isolation conditions (Scheme ) 15b. In solution, they are fleeting and dimerize in benzene or hexane, or react with the solvent in methanol or acetic acid 15a,c. 16 Aside from the prospect to stabilize these species by encapsulation, dynamic octamine hemicarcerands 1 a – c possess another unique property that makes them useful as nanoreactor, namely the ability to alter their dynamics and stability through addition of acid and/or water, which will influence their molecular recognition properties and guest exchange kinetics 12d,q.…”

Section: Introductionmentioning

confidence: 99%

Assembly of Water‐Soluble, Dynamic, Covalent Container Molecules and Their Application in the Room‐Temperature Stabilization of Protoadamantene

Zhang

Sun

Efremovska

et al. 2012

Chemistry A European J

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The thermodynamically controlled reactions of water-soluble tetraformylcavitand 2 with two equivalents of H(2)N(CH(2))(n) NH(2) (n=2-4) in the presence of a suitable templating guest give hemicarceplexes 1 a-c⋅guest, the yield of which depends on the match between size and shape of the guest and that of the inner phase. These hemicarceplexes are dynamic and dissociate upon addition of acid and reform upon basification. In water, they exchange guests through temporary hydrolysis of imine bonds. To test 1 b as molecular reaction flask, 3-noradamantyldiazirine 6 was encapsulated and photolyzed at 350 nm to produce Bredt olefin protoadamantene 5 and 1-noradamantyldiazomethane 8 in a 4:1 ratio. Encapsulated protoadamantene is stable for days at room temperature in (CD(3))(2)SO/CD(3)CN (t(1/2) = 5.5 days) and has a lifetime of several minutes in D(2)O.

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More on Adamantene

Cited by 20 publications

References 3 publications

The quest for a triplet ground‐state alkene: Highly twisted C═C double bonds

The quest for a triplet ground‐state alkene: Highly twisted C═C double bonds

Experimental and Computational Mechanistic Investigation of Chlorocarbene Additions to Bridgehead Carbene–Anti-Bredt Systems: Noradamantylcarbene–Adamantene and Adamantylcarbene–Homoadamantene

Assembly of Water‐Soluble, Dynamic, Covalent Container Molecules and Their Application in the Room‐Temperature Stabilization of Protoadamantene

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